Core H: Cognition SUMMARY The Cognition Core of the Dominantly Inherited Alzheimer Network (DIAN) is a newly formed core that will serve the overall grant by overseeing rater training and maintaining rigorous quality control (QC) and documentation standards that ensure the fidelity of longitudinal cognitive assessments. A primary goal of the core is to revise the cognitive assessment battery to align with scientific aims and minimize participant burden. We will remove burdensome and insensitive measures and incorporate novel measures and novel assessment methodologies that are more sensitive to early cognitive changes. These methodologies will improve reliability in measurement of the key features of autosomal dominant Alzheimer disease (ADAD). The assessment of cognition is central for achieving the scientific aims of all DIAN Projects and Cores. The Cognition Core will work with the Project and Core leaders to ensure that fully validated cognitive data is available for DIAN data freezes and provide guidance on appropriate cognitive measures and data analyses to support project and core aims. Due to the unique value of the ADAD population, there is great enthusiasm from DIAN investigators and external investigators to add novel cognitive measures to DIAN. However, any revisions or additions to the battery can be extraordinarily complicated in a global study like DIAN. The Cognition Core has formed an advisory board including leaders in clinical neuropsychology and cognitive psychology from academic institutions and industry who have specific expertise in global AD studies, clinical trials, computerized assessment, and remote technologies. In consultation with the advisory board, the Cognition Core has developed a formalized process for evaluating, piloting, and integrating new cognitive measures. This process involves scrutiny of preliminary data, test characteristics, availability of translations and suitability for remote test administration. A goal of the DIAN renewal is to harmonize DIAN across all affiliated studies to maximize the power of this remarkable dataset for insights into the essential characteristics of ADAD and to support more effective clinical trials. A dedicated Cognition Core serves this mission directly by creating multiple efficiencies across DIAN, the DIAN-Trials Unit (DIAN-TU) and the DIAN Expanded Registry (DIAN EXR). Core measures of the cognitive assessment battery in DIAN formed the basis for the DIAN-TU battery, but there remain crucial differences in the assessments collected, differences in rater training and certification, differences in QC processes, and DIAN only recently has implemented a rigorous system of documentation. A dedicated core will align these procedures, improve QC processes, and facilitate communications between sites and the DIAN Coordinating Center, thus achieving a critical aim of the core: to improve the rigor and reproducibility of cognitive data collected across all DIAN studies.